The present invention relates generally to the field of storage area networks (SANs), and more particularly to control of storage controller bandwidth. A storage area network is a dedicated network that provides data storage, which is typically in the form of consolidated, block level data storage. SANs are often used to enhance storage devices, such as disk arrays, tape libraries, and optical jukeboxes. Typically, SANs are accessible to servers so that the devices appear like locally attached devices to the operating system. A SAN typically has its own network of storage devices that are generally not accessible through the local area network by other devices. Typically, a SAN does not provide file abstraction, but, rather, only block-level operations. However, file systems built on top of SANs do provide file-level access, and are known as SAN filesystems or shared disk file systems.
Emergence of Converged Enhanced Ethernet (CEE) with 10/40/100 Gbps (gigabits per second) Ethernet along with 10/40/100 Gbps FCoE (Fibre Channel over Ethernet), 16 Gbps Fibre channel have led to creation of truly heterogeneous SAN fabrics. These heterogeneous SAN fabrics typically include a mixture of Fiber Channel and Ethernet networks. Even on the same Ethernet backbone, storage protocols like Fibre Channel Over Ethernet (FCoE) and iSCSI are used to transport SAN traffic over the same Ethernet infrastructure. The CEE network can be connected to a native Fibre channel network using Fibre Channel Forwarders (FCFs) to create a heterogeneous fabric consisting of both Ethernet and Fiber Channel fabrics. Some currently conventional SAN fabrics include a combination of 4 Gbps/8 Gbps/16 Gbps fiber channel elements and 10 Gbps/40 Gbps/100 Gbps ethernet elements.
Currently conventional storage controllers do not “understand” the SAN fabric topology. The storage controller simply transmits as much data as it is being requested by the host. Under heavy load the amount of data it can transmit either gets limited by its own link bandwidth or the link bandwidth of the host. When the link bandwidth of the host is less than that of the storage controller, the storage controller's data transmission is limited by the switch that employs congestion control techniques. The storage controller should avoid saturating host port links.
Currently conventional storage controllers do not “understand” the SAN fabric topology. The storage controller simply transmits as much data as it is being requested by the host. Under heavy load the amount of data it can transmit either gets limited by its own link bandwidth or the link bandwidth of the host. When the link bandwidth of the host is less than that of the storage controller, the storage controller's data transmission is limited by the switch that employs congestion control techniques.